He was the God who protected the forests, the countryside and the flocks of sheep and goats, especially from wolf attacks. We could compare this divinity to Pan, since he was usually portrayed as a young man with horns and hooves, and who also played a flute.
Lupercalia was a festival in which pagan priests, also called Luperci, would sacrifice a baby goat on Palatine Hill. The sacrifice had to happen in the Lupercale, the cavern were the legendary founders of Rome, Romulus and Remus, had been fed by the she-wolf (‘lupa’ in Italian). The bloody knife, just used for killing the animal and making an offer to the gods, was then run across the faces of 2 young aristocratic boys. While cleaning their faces with wool soaked in milk, as the ritual goes, they were supposed to laugh.
The goat’s hide was then cut in strips which were used as whips by the pagan priests (Luperci), who would run around the city, almost naked, whipping all the women who were looking for a blessing of fertility.
The Lupercalia was celebrated until the 5th century AD (one of the longest-lived pagan festivities ever), until Pope Gelasio I prohibited any Christian from taking part in the events, proclaiming the pagan idols demons.
Gelasio substituted the Feast of fertility and femininity with an opposite holiday, to remember the Purification of the Virgin Mary, to be celebrated on the same days as the Lupercalia.
Tradition says that it was also Gelasio who created St. Valentine’s Day, dedicating the holiday to a Saint who spent his entire life proclaiming the importance of love- not just romantic love between a man and a woman, but the Christian sentiment of love (“Love thy neighbor as thyself”.) This choice could have been meant as an example of temperance and modesty for all lovers to be protected by their patron Saint.